Small animal anesthesia machine

ABSTRACT

Anesthetizing apparatus capable of use with anesthetic agents requiring an in-line arrangement, as well as those necessitating the use of an out-of-line arrangement. The apparatus includes the main body member having a plurality of internal passages which provide a closed system or circuit, and further defining two separate and distinct paths within said circuit. Waste gas purging means, vaporizer means and oxygen inlet means are connected to the body member in communication with said int

Elite Sttes atet I151 9 9 37 Johnson Aug. 29, 1972 [54] SMALL ANIMALANESTHESIA Primary Examiner-Richard A. Gaudet MACHINE AssistantExaminer-G. 1F. Dunne [72] Inventor: Donald W. Jon, c/o SnyderAttorney-OlsonTrexlflwoltersgzBushneu Manufacturing Co., Inc. 1458 5thSt. N.W., New Philadelphia, Ohio [73] Assignee: Snyder ManufacturingCompany,

7 r 7 Inc., New Philadelphia, Ohio [22] Filed: Nov. 13, 1969 [21] Appl.N0.: 876,335

[52] US. Cl ..128/188 [51] Int. Cl. ..A61n 17/00 [58] Field ofSeai-ch..128/188,186,194,l45.6, I

rfiw W 1 9l A [56] Reterences Cited UNITED STATES PATENTS 2,586,6772/1952 Marrett ..128/188 3,017,881 l/1962 Smith ..128/188 2,839,0556/1958 Marrett .,.128/188 FOREIGN PATENTS OR APPLICATIONS 1,106,0355/1961 Germany ..128/188 1,193,522 3/1970 Great Britain 128/188Anesthetizing apparatus capable of use with anesthetic agents requiringan in-line arrangement, as well as those necessitating the use of anout-of-line arrangement. The apparatus includes the main body memberhaving a plurality of internal passages which provide a closed system orcircuit, and further defining two separate and distinct paths withinsaid circuit. Waste gas purging means, vaporizer means and oxygen inletmeans are connected to the body member in communication with saidinternal passages. .The apparatus further includes control means forselectively providing' one or the other of said paths for the carbondiox ide free waste gas leaving the purging means. Accordingly, purgedwaste gas to be ire-circulated to the animal can be either mixed withoxygen and then subjected to the vaporizer (in-line arrangement), orsaid gas may bypass the vaporizer and be mixed with oxygen that haspreviously been subjected to the vaporizing process (out-of-linearrangement). in addition there is provided a novel construction for themain y member, wherein a pair of opposed plate members are utilized, onesaid member having channels formed therein such that upon assembly saidchannels are covered to define the internal passages of the system 16Ciaims, 111 Drawing i I SMALL ANIMAL ANESTHESIA MACHINE BACKGROUND OFTHE INVENTION The present invention relates to anesthetic apparatus forsmall animals or the like. More particularly, this invention providesapparatus of the aforementioned general type which can be employed withthose anesthetic agents requiring an in-line arrangement,

as well as those requiring an out-of-line system, as will be explainedmore completely hereinafter.

Anesthetizing apparatus of the type under discussion normally employ theuse of a closed system or circuit. That is, the exhaust gases exhaled bythe animal are circulated through a purging agent to remove the carbondioxide, such that the purged gas, except for its oxygen deficiency isfit for rebreathing. Accordingly, since all of the anesthetic gas is notabsorbed by the animal upon each instance of inhaling, this regenerationprocess permits unabsorbed anesthetic gas that is exhaled to be reused,thus markedly reducing the amount of anesthetic agent that is needed.This factor is especially important in the case of certain recentlydeveloped anesthetics, such as halothane which are expensive and must beconserved, if economical operation is to be realized.

Of course, before the purged waste gas is recirculated to the animal, itis necessary that oxygen be added thereto, in order to sustain theanimal. Further, since the animal will also absorb quantities of theanesthetic gas, it is necessary to employ vaporizing apparatus, whichpermits the introduction of anesthetic gas into the system undercontrolled conditions. However, once a desired state of anesthetizationis reached, the addition of anesthetic gas can be terminated with theunabsorbed gas maintaining the desired condition for a short period oftime.

While numerous anesthetics can be employed in the anesthetizing of smallanimals, these can be broken down into two general groupings; thoserequiring an in-line system, and those requiring an out-of-linearrangement. With an in-line setup, the vaporizer apparatus for theanesthetic agent is positioned in the inhalation portion of the system.That is, after the carbon dioxide has been removed from the exhaust gasby the purging agent, and the required amount of oxygen introduced intothe system, the resulting gaseous combination, or a portion thereof, isexposed to the vaporizing process to add anesthetic gas thereto prior torebreathing by the animal. On the other hand, with an out-of-linearrangement, only the newly introduced oxygen is subjected to thevaporizing operation with the resulting mixture of oxygen and anestheticgas then being combined with the purged waste gases. That is, theexhaled, purged waste gases which contain a quantity of anesthetic gas,are not resubmitted to the vaporizing process.

Two examples of the aforementioned types of anesthetic agents used toanesthetize both large and small animals are methoxyflurane andhalothane. Methoxyflurane is illustrative of the agents which requirethe use of an in-line arrangement, while halothane represents thoserequiring an out-of-Iine system.

Both of the above-mentioned anesthetizing agents have certain desirablecharacteristics such that a veterinarian may use both during hisday-to-day practice, depending upon his preference, or the choicedictated in relation to the type of animal encountered and the conditionthereof. Halothane permits rapid induction, free from excitement, sinceit is non-irritating to the mucous membranes and the eyes, and does notpossess an offensive odor, factors which often excite an animal andcause him to struggle. In addition, halothane is non-explosive andnon-flammable. Also, it will vaporize quickly, and due to its potency, adeep anesthesia can be induced quite rapidly and easily. Methoxyflurane,on the other hand, is somewhat less expensive than halothane, and hasbeen in use for a considerably longer period so veterinarians are moreskilled in its use and control. Accordingly, while methoxyflurane doesnot possess many of the ad- .vantages of halothane, it is preferred bysome cost of anesthetizing equipment, and the necessity of utilizingagents requiring different types of arrangements, make it extremelyadvantageous for a veterinarian to have one machine capable of handlingboth types of anesthetizing agents.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS FIG. I is a partialperspective view illustrating an embodiment of the present inventionbeing employed to anesthetize a dog or the like;

FIG. 2 is a perspective view of the body member of the apparatus of thepresent invention with the upper plate portion removed, and illustratingthe construction of the lower plate portion; I

FIG. 3 is a top plan view of the body member of the present inventionwith the various internal passages or the like illustrated in dottedoutline;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3 in thedirection indicated;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 3 in thedirection indicated;

FIG. 6 is a partial sectional view taken along the line 6-6 of FIG. 5 inthe direction indicated and illustrating the alternative position of thecontrol means for the purging agent container;

FIG. 7 is a sectional view taken along the line 7-7 of FIG. 3 in thedirection indicated;

FIG. 8 is a partial sectional view taken along the line 8-8 of FIG. 7 inthe direction indicated, and illustrating the vane member employed incontrolling the vaporizer arrangement;

FIG. 9 is a sectional view taken along the line 9-9 of FIG. 7; and

FIGS. MI and 11 are perspective views illustrating the construction ofthe wick element employed with the vaporizer apparatus of FIG. 7.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring now to the drawingsin more detail, FIG. 1 shows a preferred form of the anesthetizingapparatus for the present invention being used on a dog, said apparatusbeing designated generally 20. Apparatus 20 includes primarily a mainbody member 22, a Y- branched tubular arrangement 24, a container 26 forthe purging agent, oxygen inlet means 25, and a vaporizer unit 28.

The body member 22 has an inlet port 30 and an outlet port 32 betweenwhich there are provided a series or system of internal passageways thatdefine, with the container 26 and the vaporizer unit 28 a pair of closedcircuit paths for the overall system. The oxygen supply means 25, whichwill be discussed more completely hereinafter, is also connected withthe internal passages of the body member 22 so that a metered supply ofoxygen may be continuously introduced into the system.

Quite briefly then, the tubular arrangement 24 provides means wherebyexhaled waste gases are introduced into the body member 22 by means ofthe inlet port 30. These gases then pass to the purging agent container26 where the carbon dioxide is removed. Next, the purged gas, whichcontains an in- SUffiClfiHt amount of oxygen to sustain the animal, ismixed with newly added oxygen supplied to the system by the inlet means25. Also, subsequent to purging, but prior to inhalation or rebreathing,additional amounts of anesthetic gas are introduced into the system bythe vaporizer unit 28, as required.

Should the animal stop breathing during the period it is anesthetized, abag element 23 as shown in FIG. 1 may be employed to induce artificialrespiration. The bag 23 is connected to port in the body member 22,which in turn communicates with the internal passages. Thus, theinterior of bag 23 is in communication with the remainder of the system,such that by the squeezing thereof, the internal pressure of the gas maybe raised to expand the animals lungs and induce breathing.

More specifically, considering the apparatus 20 in detail, the tubingarrangement 24 includes an endotracheal portion 36, disposed within thetrachea of the animal, an exhalation branch 38 connected to inlet port30, and a corresponding inhalation branch 40 connected to the outletport 32 of the body member 22. A valving arrangement is associated witheither the Y- branch portion of the assembly 24, or with the ports 30and 32, such that gas can travel in only one direction in the branches38 and 40. In this regard, the illustrated embodiment employs one wayvalve assemblies 42 and 42 in conjunction with said ports 30 and 32 aswill be discussed hereinafter.

Accordingly, the exhaled waste gases will travel from the endotrachealtube 36 into the exhalation portion 33, and from there to the interiorbody member 22 via the inlet port 30. Next, the waste gas is subjectedto the purging agent, i.e., soda lime, carried by the container 26 inorder to remove the carbon dioxide therefrom and the requisite amountsof oxygen and anesthetic gas are added thereto. The resulting gaseousmixture, which is now reconstituted and fit for breathing, is thenintroduced into the inhalation branch 40 of the tube arrangement 24 bymeans of the outlet port 32.

Regarding the introduction of the anesthetic agent to the gas in thesystem, it should be recalled that in an out-of-line arrangement, theoxygen being introduced, or a portion thereof, is subjected to thevaporizer unit 28 prior to being mixed with the purged waste gas. On theother hand, with an in-line system, the purged waste gas is mixed withthe requisite amount of oxygen, and the resultant gaseous combination isthen subjected to the vaporizing process in order to add the anestheticagent to the overall mixture. Thus, with this alternate mode ofoperation in mind, attention is now invited to FIG. 2.

FIG. 2 illustrates the manner in which the internal passages of thebody. member 22 for the present invention are defined. The exactfunction of these various passages and their cooperation regarding theoverall operation of the apparatus will be detailed sub- I sequently.However, it should be noted at this time that the member 22. iscomprised of interconnected upper and lower platelike sections 22' and22"", shown in disassembled relation in FIG. 2. The lower section 22"has a plurality of channels or relieved portions formed therein.Accordingly, upon assembly of the upper section 22' thereto, thesevarious channels are covered to define a plurality of interconnectedinterior passages.

Turning now to FIGS. 3-7, the specific construction of the disclosedembodiment of body member 22 and its function relative to the purgingmeans and the vaporizing means will be considered in'detail.

As can be seen from FIG. 3, the body member 22 is of a substantiallyflat, rectangular construction. Inlet port 34) is in the upper left-handportion of the figure, as viewed, and is connected to the exhalationbranch 38 of the tube assembly 24 to receive the waste gases exhaled bythe animal being anesthetized.

Associated with the inlet port 39 is the one-way inlet valve arrangement42 mentioned previously which permits the waste gas to enter the body22, but precludes the withdrawal of gas therefrom when the animalinhales. Inlet port 30 opens into a transverse passage or bore 44 formedin the body 22, and closed by a cap arrangement 46. Disposed coaxiallyin the passage 44 is a tubular restricter or deflector member 48 whichhas a portion of its lower wall removed to provide an opening 50 whichcommunicates with the inlet port 30. Also it should be noted that thebottom wall of bore 44 closes the lower end of said restricter 48.

A disc-like valve element 52 is positioned proximate the upper end oredge of restricter 48 and is adapted to rest thereupon in blockingengagement with respect to said open upper end. The disc valve 52includes a stem 54 which is received in a guide socket 56 formedintegral with the cap arrangement 46. The length of stem 54 is less thanthe depth of socket 56 such that the disc 52 is free to reciprocaterelative to the open upper end of the restricter 48, alternately toblock or permit communication through the restricter 48.

Further, as is illustrated in H6. 5, there is provided a L-shapedpassage 60, one end of which communicates with the transverse bore 44,the other opening to the bottom surface of body member 22. Also, itshould be noted that the outer diameter of the restricter 48 is lessthan the diameter of the bore 4%, such that with said restricter iseccentrically positioned in said bore as illustrated, communicationbetween the interior thereof and the L-shaped passage 60 can beestablished when the disc valve 52 is in the raised position. In orderto properly position restricter 48 as discussed, there is provided anaperture positioning washer 62 that is carried by the cap assembly doand receives restricter 48 in surrounding engagement.

Accordingly, as waste gas enters the body member 22 via port 38 it willbe deflected upward by the restricter 48 to unseat the disc valve 52.Once the disc valve 52 is unseated, the gases will flow over the upperedge of restricter 48 and downwardly between said restricter and thebore dd into the L-shaped passage 60. However, when the animal inhales,any tendency to draw gases in a reverse direction, viz., out of the L-shaped passage60, will be precluded by the seating of the disc valve 52on the upper open end of restricter 48. Thus, it can be seen that thevalve assembly 42 only permits gas to enter the body member 22, andpositively precludes any withdrawal therefrom.

Coupled to the L-shaped passage 60 is a section of flexible hose 64which communicates with the inlet opening 66 in the purging agentcontainer 26, as seen in FIG. 5. Accordingly, after the gases enter thebody member 22 through the one-way valve arrangement 42 it then willpass through the section of tubing 64 and into the purging agentcontainer 26.

The purging agent container 26 is of a generally tubular configurationand is carried by the lower portion of the body member 22. The means formounting said container 26 to the body member 22 may be of any knownform, the illustrated arrangement employing a mounting disc bolted tothe body member 22 and engaging an annular flange 70 formed on the upperopen end of the container 26.

A permeable screen element 72 is carried by container 26 which in effectdivides the container into an upper compartment 74 and a lowercompartment 76. Disposed in the upper compartment 74 is a quantity ofpurging agent 78, such as soda lime or the like. The lower compartment76 has the inlet opening 66 formed therein, such that waste gas willenter said compartment 76 and will pass upwardly through the screen 72and the purging agent 78. The purging agent 78 absorbs the carbondioxide from the waste gases, such that the gas leaving container 26 issubstantially fit for rebreathing, except for its low oxygen contentoccasioned by the absorption thereof by the animal.

In the illustrated form of the invention, the upper open end of thecontainer 26 is received within a bore 8%) defined by the body member22. Said bore being sealed from the surrounding environment by means ofthe mounting arrangement employed for the container 26 such that escapeof the purged gas to the atmosphere is precluded. A rotatable platemember 82 is carried by the body member 22 in juxtaposition to thebottom wall of the bore 80, and in superposed relation to the upper openend of container 26. The plate member 82 has an aperture 84 formedtherein, which aperture provides the means of communication between thepurging agent container 26 and the remainder of the internal closedsystem. In this regard, it should be noted that by rotation of the platemember 82, the disposition of aperture 84 relative to the internalpassages formed in member may be controlled, such that the purged gasemitted from container 26 may be directed to a desired one of saidpassages.

Directing attention to FIGS. 3 and 5, a control knob 86 may beassociated with said plate 82 to facilitate movement thereof. Also, ifdesired, a portion of the periphery of the plate 82 can be removed toaccommodate a stop member 88 integrally formed on the body member 22.Accordingly, the interaction between said stop member 88 and plate 82defines the limits of movement of said plate, which limits are selectedto assure alignment of aperture 84 with a desired internal pasage.

Directing attention now to FIGS. 2 and 3, adjacent outlet port 32 thereis provided a one-way valve assembly which is substantially identical tothe vaforediscussed assembly 62, and accordingly is designated 42. Theassembly 42' provides communication between the outlet port 32 and theinterior passages of the body member 22. In this regard, the position ofthe restricter member 46' is reversed with respect to the correspondingelement of arrangement 62, as can be seen in FIG. 7. Thus, gas can onlybe drawn out of the outlet port 32 upon inhaling by the animal, andentry of exhaust gas via port 32 is positively precluded by the one-wayvalve arrangement 42'. Further, since the arrangement 42 issubstantially identical to the previously discussed valve construction42, the elements thereof have been designated by like reference number,primed and a detailed discussion of the structural feature is deemedunnecessary.

Considering now the specific construction of the internal passages ofbody member 22, associated with the one-way valve assembly 42 is anelongated outlet passage 99, which extends for substantially the entirelength of the body member 22 opening at one end thereof to provide aport 92 for the reservoir bag 23. In communication with the elongateoutlet 96 are a pair of separate and distinct passages 94 and 96. Boththe passages 94 and 96 communicate with the purging agent containerreceiving bore 80. Thus, it can be seen that communication between theinterior of said container 26 and either of the respective passages 94and 96 can be established, depending upon the relative disposition orpositioning of the control plate 82. That is to say, when plate 82 is inthe position illustrated in FIG. 3, aperture 34 is aligned with the endof passage 96 to establish communication between said passage and theinterior of the container. On the other hand, in the positionillustrated in FIG. 6, plate 82blocks communication between saidcontainer 26 and the passage 94 while the aperture 84 is aligned withpassage 94 to establish communication therebetween.

It will be recalled, that the present apparatus 20 is designed tooperate as an in-line or an out-of-line system, with respect to therelative disposition of the vaporizer assembly 28. Accordingly, stillwith reference to FIGS. 2 and 3, the body member 22 further includes avaporizer control chamber 100 disposed intermediate the points whereinpassages 94 and 96 merge or connect with the elongate outlet passage 90.In the floor of the chamber ltltl there are provided a pair of ports oropenings 1 .02 and 104 which serve as the inlet and outlet,respectively, for the vaporizer unit 28. The general overallconstruction of the vaporizer apparatus of the present invention will bediscussed in detail hereinafter. However, it can be seen that with thevaporizing inlet and outlet ports disposed intermediate the respectivepassages 94!- and 96, and considering the closed circuit path that thegas must take, it can be seen that only when the purged waste gas ischanneled through the passage 96 can it thus be subjected to thevaporizer apparatus 28. When the elements of apparatus 28 are sodisposed, it functions as an in-line arrangement. On the other hand,when the purged waste gas from the container 26 is directed to thepassageway 94, the vaporizer control chamber 106 is effectively bypassedsuch that the purged gas can pass directly to passageway 96 and outthrough port 32. Accordingly, for purposes of identification hereinafterthe passageway 96 is termed the in-line" passageway,

while passageway 94 is designated the out-of-line" passageway.

Before considering the construction of the vaporizer apparatus 28 andits manner of control and its relation to the anesthetizing process, itis deemed advisable to first consider the oxygen inlet means 25 referredto previously. Recalling the prior discussion of the anesthetizingprocess with a closed circuit system of the type under discussion, it isnecessary to continuously add oxygen to the gaseous mixture that is tobe recirculated to the animal. With an in-line arrangement, the oxygenis first mixed with the purged waste gases and the resultingcombination, or selected portions thereof are subjected to thevaporizing process. With an outof-line arrangement, only the oxygenbeing introduced to the system is passed through the vaporizer unit 28,and the resulting mixture of oxygen and anesthetic gas is then mixedwith the purged waste gases.

Accordingly, in conjunction with the oxygen introducing means 25,attention is now directed to FIGS. 2, 4 and 5. Considering first P16. 2,it can been seen that there is provided a pair of passages 110 and 112,both of which communicate only with the in-line passage 96. Therefor,since it is these passages that are utilized in the introduction ofoxygen into the system, oxygen can only reach the downstream portion ofpassage 96 by passing through chamber 100.

Considering now FIG. 4, the oxygen inlet means 25 include an inlet line114 which communicates with a flow-meter 1 16 through a bypass valve118. Under normal conditions, the valve 1 18 is positioned to directoxygen from line 114 into the flow-meter 116. The flowmeter 116 includesa control dial 120 which is employed to adjust the rate of flow ofoxygen from the meter to the system. The oxygen inlet passage 112 isconnected to the outlet of the flow-meter 1 16 by means of a section ofconduit 122, and a fitting 124 in order to introduce oxygen into passage1 12.

Under emergency conditions, however, where the anesthetized animal isreceiving less than the required amount of oxygen, it is necessary tobypass the flowmeter 116 in order to flood the system with as muchoxygen as possible. To attain this result, the valve 118 is providedwith an alternate outlet port 126 which in turn is connected directly tothe oxygen inlet passage 1111, rather than the flow-meter 116. Thedirection of flow through the bypass valve 113 is controlled by a togglelever 128, such that under emergency conditions the operator can flipsaid lever 12% to bypass the flowmeter and feed substantial quantitiesof oxygen into port 126 and the associated passage 110.

Since the present invention employs a closed system, and oxygen iscontinuously being introduced into the system, a degree of pressurebuild-up will occur. To accommodate this build-up, the apparatus 20includes a relief valve assembly 130 illustrated in FIG. 5.

The relief valve assembly 130 communicates with the in-line passage 96through a port 132 formed in the body member 22. Associated with saidport 132 is a tubular element 134 which has its upper end closed by avalve member 136. Valve member 136 is biased into closed sealingengagement with the element 134 by means of a spring 138. Thus, when theoperating pressure of the passage in exceeds a predetermined levelestablished by the biasing force of spring 138, the valve member 136will be moved outwardly to allow gas to escape, so that the internal gaspressure may be maintained at a point within a desired range.

It will be recalled, however, that under certain conditions it isnecessary that respiration of the animal be induced by use of areservoir bag 23. Accordingly, since the success of this processrequires a build-up of gaseous pressure to expand the animals lungs, itis necessary to disable the relief valve assembly 13%. To provide forthis, the valve element 136 includes a stern 1 10 which extends upwardlyand is connected to a toggle lever M2 that has a cam-like end portion144. Thus, in the illustrated position of the toggle lever 142, therelief valve is in the operating condition, however, should lever 1 1-2be raised, the valve element 136 will be locked in position, so that abuild-up in the operating pressure in the system can be achieved.

Turning now to FIG. 7, this figure is a sectional view taken through theapparatus proximate the outlet passage 90,. and illustrates in detailthe construction of the one-way valve arrangement 42 as well as thevaporizer apparatus 28, the latter of which is to be discussed in detailhereinafter.

The vaporizer apparatus 28 includes a container for the anesthetic agentwhich is carried by the body member 22 by means of the disposition ofthe upper open end thereof in a socket 152 defined by said body. While athreaded connection isshown, various means may be employed to effectthis connection. The aforementioned vaporizer control chamber 1116 isaligned with the socket 152 such that a common wall portion defines thebottom of socket 152, as well as the lower wall of the chamber 101).

inviting attention now to the upper right-hand portion of FIG. 7, asviewed, there is illustrated filler means which permit the filling ofthe container 150 with the anesthetic agent without disconnecting saidcontainer from the body member 22. The filler means includes a passage151 formed in the upper half of the body member 22. The passage 151 hasone end opening to the top surface of the body member and another endaligned with the inlet port 1112 of the vaporizer unit 28. The removableplug member 153 is provided in blocking relation to the end of passage1511 opening to the upper surface of body member 22. Accordingly, whenit is desired to till the container 150 with the anesthetic agent, theplug 153 is removed and the anesthetic agent poured into the open end ofpassage 151 whereby it will be dispensed downwardly through the inletpassage 1112 into the container 150.

Disposed within the container 150 is a wick assembly 154 whichfacilitates vaporization of the anesthetic agent. The wick assembly,which is illustrated in perspective in FIG. 1b, includes a main tube156, a wick support member 158 and inner and outer wick elements 160 and16 1. The main or entry tube 156 has its upper end coupled to a tubularextension 168 on body member 22 which defines the vaporizer inlet port102, thus establishing communication between the chamber 101) and saidentry tube 156. The lower portion of entry tube 156 has port 170 formedtherein at a location below the wick support member 158. Thus, gasexiting from the tube 156 will pass through both the inner wick elementi6 3 and the outer wick element 164 before exiting from the outlet port1.

Considering now FIG. ll, the general construction of the wick elementsres and 164- can be viewed. in this regard, each element is comprised ofa meshlike wire frame 171 which has fibrous strands of wicking 172wrapped therearound, as illustrated.

In order to control the vaporizing operation, a vane element 18% isdisposed within the chamber 100, as illustrated. It will be recalledthat during the anesthetizing procedure it is often desirable to divertall of the gas to the vaporizer unit 28; however, under certaincircumstances it is desirable to bypass the vaporizer altogether, ormerely direct a portion of the gaseous product from passageway 96 intounit 28.

The vane 380, as will be noted, is narrow at one end 182, while theopposite end 184 is of a substantially broad triangular configuration.The vane is rotatably mounted within the chamber lilll and operablyconnected to an actuator knob 12%, such that its position relative tosaid chamber 1% and the inlet and outlet openings 1G2 and M94 of thevaporizer unit can be adjusted. The thickness and configuration of thevane 180 is such that when the position illustrated in FIG. 3, directcommunication between the downstream portion of passage 90 and thepassageway 96 is blocked by said vane, the only path of communicationbeing through the vaporizer apparatus 28. However, referring now to FIG.8, when the control vane 18% is moved to the position illustrated indotted outline, the respective end portions 184 and 182 blockcommunication between the vaporizer and the control chamber 100, thuspermitting any gaseous product in the passageway 96 to flow directlythrough chamber llltl into the downstream portion of passage 90, thusbypassing the vaporizer 28 on its way to the outlet port 32. Further, itshould be noted that by adjusting the position of vane 13%) between thetwo positions illustrated in FIG. 8, the amount of gaseous productallowed to bypass the vaporizer 28 can be controlled. That is,considering the full line illustration of said vane 180, as it is movedin a clockwise direction, the narrow end 182 will be displaced from thevertical wall of outlet passage 90 so that a portion of the gas enteringthe control chamber 1% will be permitted to bypass the vaporizer whilethe remainder is diverted to the inlet opening W2. Obviously, as thedegree of clockwise rotation increases so does the amount of gaspermitted to bypass the vaporizing apparatus 28. It also should be notedthat the clockwise rotation of the vane 186 under discussion also causesthe broad triangular shaped portion 184 to cover progressively thevaporizer inlet port 102, same bemg completely blocked upon theengagement of the narrow end 1 .82 with the arcuate sidewall of thecontrol chamber llll).

Thus, it can be seen that by proper employment of the vane 1843, theamount of anesthetic agents being introduced into the system in eitherthe in-line or outof-line condition can be controlled. On the otherhand, once the animal has reached a desired state of anesthetization,the vane can be moved to the blocking position illustrated in full linein FIG. 8, such that the vaporizer apparatus is bypassed completely, theunabsorbed anesthetic agent in the waste gas serving to maintain thisstate of anesthetization for a period of time.

iii

the trachea of the animal, and the inhalation and exhalation branches 38and 4b are connected to the inlet and outlet ports 3@ and 32 of theapparatus 20, as shown in FIG. ll. At this point, the control vane 180is in the blocking position such that the vaporizer unit 28 is out ofcircuit with the internal passages of body member 22. Also, inconjunction with the disposition of the endotracheal tube, the oxygensupply is turned on such that the flow-meter M6 is introducing acontinuous, regulated supply of oxygen into the passageway 96 via thepassage 112. As the animal breathes in its tranquilized state, theexhaled waste gases will enter the inlet port 3% and will be passedthrough the purging agent 78 carried in container'26 to remove carbondioxide therefrom. After removal of the carbon dioxide, the purged wastegases pass into the in-line passage 96 through the opening 34 in thecontrol plate 82. As the purged waste gas travels the length of passage96 it is mixed with the newly introduced oxygen being introduced intopassage 96 by means of the passageway 1112. From there, the gaseousmixture enters the upstream end of the outlet passage'90, and from therethe control chamber 1%, bypassing the vaporizer due to the position ofthe vane 18 3. Upon leaving the control chamber Mill, the mixture thentravels the length of the outlet passage and passes out of body member22 through port 32 into the inhalation branch 40.

After all the initial connections have been established, the pressurerelief valve H30 is closed and the reservoir bag 23 is squeezed firmlyto increase the pressure in the system and thereby permit detection ofany leaks, or the like. Once the operator is satisfied that the systemis substantially leak-free, the pressure relief valve 13% is opened.This feature in conjunction with periodic emptying of the reservoir baginsures proper denitrogenation of the system and prevents hypoxia.

Accordingly, with the animal tranquilized and the operator satisfiedthat the system if functioning properly, he then connects the vaporizerapparatus 28 into the system by use of the control dial ll86 whicheffects the aforediscussed counter-clockwise rotation of vane 184]).Thus, the mixture of purged waste gas and oxygen entering the upstreamportion of passage 90 from the in-line passage 96 will be diverted bythe vane portion 132 into chamber W0 and from there through the inletport 1W2. Looking now to H6. '7, the gaseous mixture will then bedirected downwardly into the entry tube 156 of the work assembly, andthen from there out through the aperture 17th and through the workelements. By this operation, the anesthetic agent is vaporized andcombined with the gaseous mixture which leaves the vaporizer unit 28through the outlet port Md, and then passes into the outlet passage 90.The resulting combination including the anesthetic agent then passes outof the body member 22 to the animal.

Considering now the out-of-line condition, the steps for preparing theanimal for anesthetization are identical to those described above. As tothe apparatus 20, the indicator knob 86 is turned approximately 90 in aclockwise direction, such that the aperture 84 of plate 82 is alignedwith the passage 94, as illustrated in FIG. 6. Similar to the in-linecondition, the control vane 180 is positioned to block communicationwith the vaporizer apparatus 28, as shown in dotted outline in FIG. 8.The oxygen supply is connected and flow-meter 116 set so that oxygenflows into the apparatus by means of the passage 112. In this regard, itshould be noted that while the apparatusis in the out-of-line condition,oxygen can still be channeled to the outlet passage 90 through thedownstream portion of the passage 96 and chamber 100.

With the apparatus in the aforedescribed condition, after the exhaledwaste gases are purged of carbon dioxide, they are then introduced intothe passages Q4 and 96. These gases, except for their extremely lowoxygen content are fit for recirculation to the animal. The oxygendeficiency is overcome by the supply means 25, which continuously adds ametered quantity of oxygen into the internal passage system of theapparatus 20, which is mixed with the purged waste gases beingintroduced into passage $0.

When it is desired to anesthetize the animal, the control knob 186 isindexed to the position illustrated in full line in FIG. 8, thus placingthe vaporizer apparatus 28 in circuit with the path the oxygen must takein order to reach the outlet junction of passages 90 and 94. Since theoxygen cannot bypass the vane 180, it will enter the vaporizer throughthe inlet port 102 where it is subjected to the vaporizing process suchthat the resulting gaseous mixture leaving the vaporizer 28 contains asubstantial quantity of anesthetic gas. This combination of oxygen andthe anesthetic gas is mixed with the purged waste gases at the point ofjuncture of passages 90 and 94. Once the animal has reached the desiredstate of anesthetization, the vane. 180 is adjusted to the properposition to maintain said condition.

The invention is claimed as follows:

1. Apparatus for administering anesthesia to animals or the like, saidapparatus comprising: a main body member having an inlet port and anoutlet port, an internal passage means for providing a closed system foranesthetic gas; a canister connected to said body member, said canisteradapted to contain a purging agent of the type used for removing carbondioxide from the gas exhaled by said animal, said canister having aninlet in communication with said body inlet port, and an outlet openingfor communication with said internal passage means such that exhaledgases will be passed through said purging agent canister and into saidinternal passage means; a vaporizer assembly connected to said bodymember, said vaporizer assembly having inlet and outlet openings; saidinternal passage means providing two paths from said canister outlet tothe outlet port of said body member, one said path communicatingdirectly with said outlet port, and the other said path communicatingwith said vaporizing assembly; inlet means for oxygen connected to saidother path intermediate said canister outlet and said vaporizerassembly; and control means for said apparatus, including means forselectively connecting said canister outlet to one or the other of saidpaths, such that said apparatus may be used as either an inline systemor an out-of-line system for adminstering anesthetic gas, and means forselectively blocking said vaporizer assembly inlet and outlet openingsso that the amount of gas introduced into said vaporzier assembly may beregulated, and said assembly bypassed if desired.

2. Apparatus as defined in claim 1 wherein said means for selectivelyblocking the vaporizer inlet and outlet openings includes a movablemember carried by said body and adapted to have its position varied suchthat said vaporizer assembly is bypassed by the gas from the purgingagent canister, or all or a desired portion of said gas will bechanneled to said vaporizer assembly.

3. Apparatus as defined in claim 1 wherein said inlet means for theoxygen includes a flow meter for admitting a prescribed amount of oxygeninto said closed circuit.

4. Apparatus as defined in claim 3 where said inlet means for the oxygenfurther includes a valve assembly permitting the flow meter to bebypassed whereby oxygen can be introduced directly into said closedcircuit.

5. Apparatus as defined in claim 1 wherein said body member furtherincludes a reservoir bag port communicating with said other path, and areservoir bag attached to said port enabling the person administeringthe anesthestic to induce breathing in the anesthetized animal.

6. Apparatus as defined in claim 5 wherein said internal passagesfurther include a pressure relief valve, said valve including means tolock it in a closed position such that it cannot be opened upon theinducement of breathing by use of said reservoir bag.

7. Apparatus as defined in claim 1 wherein said control means forselectively connecting the canister outlet to one or the other of saidpaths includes a plate-like member having an aperture therein anddisposed atop said canister such that said aperture providescommunication thereto, said plate being selectively movable between afirst position wherein said opening operably connects the canister withone of said paths, and a second position wherein said aperture operablyconnects said canister with the other of said paths.

8. Apparatus as defined in claim ll, further including flexible tubemeans which comprise as an endotrachea member received by the animal, aninhalation branch connected to said outlet port, and an exhalationbranch connected to said inlet port.

9. Apparatus as defined in claim 1 wherein a one-way valve assemblyprovides for communication between each said inlet port and said outletport and the internal passage means.

10. Apparatus as defined in claim 9 wherein at least one of said valveassemblies includes, a restricter member disposed in the passagewaycommunicating with said port, said restricter member having a tubularwall section disposed transversely of said passageway with an opening inthe lower portion thereof so that gas may freely enter the lower end ofsaid restricter member and be channeled upwardly toward the upper endthereof, a reciprocal disc valve member engaged over the upper end ofsaid tubular restricter member enclosing said end, said disc beingdisengageable from said upper end by gas travelling through saidrestricter member, while precluding gas from entering the restrictermember from the upper end thereof, and passage means providingcommunication from the upper end of said restricter member to said bodyport.

11. Apparatus for administering anesthesia to animals, or the like, saidapparatus comprising: a main body assembly having an inhalation port andan exhalation port, internal passage means providing a closed system formovement of gas from said inhalation port to said exhalation port; acanister connected to said main body assembly and adapted to contain apurging agent of the type used for removing carbon dioxide from theexhaled waste gases of said animal, said canister having an inlet andan. outlet in communication with said internal passage means, such thatexhaled gases entering the body assembly pass through said purging agentprior to reaching said inhalation port; a vaporizer unit connected tosaid body assembly for introducing an anesthetic gas into said internalpassage means of the system; the improvement wherein said body assemblycomprises upper and lower plate sections, the surface of said lowersection confronting the upper section having a plurality ofchannelsformed therein such that upon assembly of said upper section thereto,said channels are covered to define said internal passage means.

12. Apparatus as defined in claim 11, wherein said lower sectionincludes a pair of apertures serving as inlet and outlet openings forthe vaporizer unit, and there is further provided control means forselectively blocking said inlet and outlet openings connecting thevaporizer unit to the system, whereby purged waste gases may passthrough said body assembly without having an anesthetic gas addedthereto.

13. Apparatus as defined in claim 12 wherein said lower plate sectionfurther includes a relieved portion formed in said confronting surfacesuch that upon assembly a chamber is provided which intersects saidinternal passage means, and means on the opposite surface of said lowerplate section for connecting said vaporizer unit thereto, said inlet andoutlet openings being formed in said lower plate section thus providingfor communication between said vaporizer unit and said chamber, and saidcontrol means being disposed in said chamber for selectively blockingsaid inlet and outlet openings.

14. Apparatus as defined in claim 13 wherein said chamber issubstantially circular in configuration, and said control means includea vane rotatably mounted within said chamber, said vane having a lengthproximating the diameter of said chamber.

15. Apparatus as defined in claim 11 wherein said passage means includetwo separate paths from the canister outlet to the inhalation port,-onesaid path communicating directly with said inhalation port and the otherpath being operatively associated with the vaporizer unit to provide forthe connection of said unit to the system, and means carried by saidbody assembly for selectively connecting one or the other of said pathswith said canister outlet.

16. Apparatus as defined in claim 15, further including oxygen inletmeans connected to said other path intermediate the point of connectionto said canister outlet and said inlet opening for the vaporizer unit.

Patent No. 3 ,687 ,137 Dated August 29. 1972 Inventor(s) Donald W.Johnson It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Col. 3 line 53, change "breathing" to --rebreathing-- Col. 4, line 8,change 22' to --22' C01. 9, line 24, after "when" insert --in-- Col. 11,line 63 change "vaporizing" to --vaporizer-- Col. 12, line 6 change"vaporzier" to "vaporizer-- Signed and sealed this 10th day of April1973.

LSEAL) Attest:

EDWARD .FLETCHBRJR. ROBERT GOTTSCHALK Attesting Officer Commissioner ofPatents :QQM PO-HJSO (10- USCOMM-DC 6O376-P69 u.S. GOVERNMENT PRINTINGOFFICE: 1969 o366334

1. Apparatus for administering anesthesia to animals or the like, saidapparatus comprising: a main body member having an inlet port and anoutlet port, an internal passage means for providing a closed system foranesthetic gas; a canister connected to said body member, said canisteradapted to contain a purging agent of the type used for removing carbondioxide from the gas exhaled by said animal, said canister having aninlet in communication with said body inlet port, and an outlet openingfor communication with said internal passage means such that exhaledgases will be passed through said purging agent canister and into saidinternal passage means; a vaporizer assembly connected to said bodymember, said vaporizer assembly having inlet and outlet openings; saidinternal passage means providing two paths from said canister outlet tothe outlet port of said body member, one said path communicatingdirectly with said outlet port, and the other said path communicatingwith said vaporizing assembly; inlet means for oxygen connected to saidother path intermediate said canister outlet and said vaporizerassembly; and control means for said apparatus, including means forselectively connecting said canister outlet to one or the other of saidpaths, such that said apparatus may be used as either an in-line systemor an out-of-line system for adminstering anesthetic gas, and means forselectively blocking said vaporizer assembly inlet and outlet openingsso that the amount of gas introduced into said vaporzier assembly may beregulated, and said assembly bypassed if desired.
 2. Apparatus asdefined in claim 1 wherein said means for selectively blocking thevaporizer inlet and outlet openings includes a movable member carried bysaid body and adapted to have its position varied such that saidvaporizer assembly is bypassed by the gas from the purging agentcanister, or all or a desired portion of said gas will be channeled tosaid vaporizer assembly.
 3. Apparatus as defined in claim 1 wherein saidinlet means for the oxygen includes a flow meter for admitting aprescribed amount of oxyGen into said closed circuit.
 4. Apparatus asdefined in claim 3 where said inlet means for the oxygen furtherincludes a valve assembly permitting the flow meter to be bypassedwhereby oxygen can be introduced directly into said closed circuit. 5.Apparatus as defined in claim 1 wherein said body member furtherincludes a reservoir bag port communicating with said other path, and areservoir bag attached to said port enabling the person administeringthe anesthestic to induce breathing in the anesthetized animal. 6.Apparatus as defined in claim 5 wherein said internal passages furtherinclude a pressure relief valve, said valve including means to lock itin a closed position such that it cannot be opened upon the inducementof breathing by use of said reservoir bag.
 7. Apparatus as defined inclaim 1 wherein said control means for selectively connecting thecanister outlet to one or the other of said paths includes a plate-likemember having an aperture therein and disposed atop said canister suchthat said aperture provides communication thereto, said plate beingselectively movable between a first position wherein said openingoperably connects the canister with one of said paths, and a secondposition wherein said aperture operably connects said canister with theother of said paths.
 8. Apparatus as defined in claim 1, furtherincluding flexible tube means which comprise as an endotrachea memberreceived by the animal, an inhalation branch connected to said outletport, and an exhalation branch connected to said inlet port. 9.Apparatus as defined in claim 1 wherein a one-way valve assemblyprovides for communication between each said inlet port and said outletport and the internal passage means.
 10. Apparatus as defined in claim 9wherein at least one of said valve assemblies includes, a restrictermember disposed in the passageway communicating with said port, saidrestricter member having a tubular wall section disposed transversely ofsaid passageway with an opening in the lower portion thereof so that gasmay freely enter the lower end of said restricter member and bechanneled upwardly toward the upper end thereof, a reciprocal disc valvemember engaged over the upper end of said tubular restricter memberenclosing said end, said disc being disengageable from said upper end bygas travelling through said restricter member, while precluding gas fromentering the restricter member from the upper end thereof, and passagemeans providing communication from the upper end of said restrictermember to said body port.
 11. Apparatus for administering anesthesia toanimals, or the like, said apparatus comprising: a main body assemblyhaving an inhalation port and an exhalation port, internal passage meansproviding a closed system for movement of gas from said inhalation portto said exhalation port; a canister connected to said main body assemblyand adapted to contain a purging agent of the type used for removingcarbon dioxide from the exhaled waste gases of said animal, saidcanister having an inlet and an outlet in communication with saidinternal passage means, such that exhaled gases entering the bodyassembly pass through said purging agent prior to reaching saidinhalation port; a vaporizer unit connected to said body assembly forintroducing an anesthetic gas into said internal passage means of thesystem; the improvement wherein said body assembly comprises upper andlower plate sections, the surface of said lower section confronting theupper section having a plurality of channels formed therein such thatupon assembly of said upper section thereto, said channels are coveredto define said internal passage means.
 12. Apparatus as defined in claim11, wherein said lower section includes a pair of apertures serving asinlet and outlet openings for the vaporizer unit, and there is furtherprovided control means for selectively blocking said inlet and outletopenings connecting the vaporizer unit to the system, whereby purgedwaste gases may pass through said body assembly without having ananesthetic gas added thereto.
 13. Apparatus as defined in claim 12wherein said lower plate section further includes a relieved portionformed in said confronting surface such that upon assembly a chamber isprovided which intersects said internal passage means, and means on theopposite surface of said lower plate section for connecting saidvaporizer unit thereto, said inlet and outlet openings being formed insaid lower plate section thus providing for communication between saidvaporizer unit and said chamber, and said control means being disposedin said chamber for selectively blocking said inlet and outlet openings.14. Apparatus as defined in claim 13 wherein said chamber issubstantially circular in configuration, and said control means includea vane rotatably mounted within said chamber, said vane having a lengthproximating the diameter of said chamber.
 15. Apparatus as defined inclaim 11 wherein said passage means include two separate paths from thecanister outlet to the inhalation port, one said path communicatingdirectly with said inhalation port and the other path being operativelyassociated with the vaporizer unit to provide for the connection of saidunit to the system, and means carried by said body assembly forselectively connecting one or the other of said paths with said canisteroutlet.
 16. Apparatus as defined in claim 15, further including oxygeninlet means connected to said other path intermediate the point ofconnection to said canister outlet and said inlet opening for thevaporizer unit.